1. Field of the Invention
The present invention relates to an optical receiver module for use, e.g., in optical fiber communications, etc.
2. Background Art
Japanese Laid-Open Patent Publication No. 2012-169478 discloses an optical receiver module including a photodetector. This optical receiver module has a resistor and a capacitor which are connected in series between the cathode terminal of the photodetector and the device carrier. The anode terminal of the photodetector is wire-connected to an amplifier circuit. The GND terminal of the amplifier circuit is wire-connected to the device carrier.
The above resistor serves to attenuate resonance resulting from the reflection at the input terminal of the amplifier circuit. The above capacitor serves to reduce variations in the bias voltage.
In order to stabilize the GND potential of the amplifier circuit of such an optical receiver module, it is important to reduce the length of the wire electrically connected between the GND terminal of the amplifier circuit and the carrier. However, the above disclosed optical receiver module is configured in such a manner that the wire connected between the GND terminal of the amplifier circuit and the carrier is long, resulting in an inability to stabilize the GND potential of the amplifier circuit.
Further, one known method for stabilizing the high frequency characteristics of an optical receiver module is to connect a resistance and a capacitor in series between the cathode terminal of the photodetector and the carrier. This means, however, that an electrical path (or circuit) is formed which extends from the input terminal of the amplifier circuit, through the photodetector, the resistance, the capacitor, and the carrier (GND), back to the input terminal of the amplifier circuit. The bandwidth of the optical receiver module is limited by the length of this electrical path. Therefore, in order to increase the bandwidth of the optical receiver module, it is important to reduce the length of this electrical path.
However, the components mounted on the carrier have a predetermined minimum size (e.g., 0.25 mm square), and furthermore a certain space must be provided between adjacent components to accommodate the positional tolerance of the components. These requirements result in an increase in the length of the above electrical path.